Condenser and similar tubes and their joints



Aug. 1, 1944. 2,354,900

coNDENsER AND SIMILAR TUBE's AND THEIR JoINTs F. C. WILKINSON Filed June 23, 1942 wim Patented Aug. 1, 1944 coNnENsEa nm suman 'runas AND 'raam .roms

Francis Clarence Walter Wilkinson, Farnham Oommo England Application zclaiml.

This invention relates to liquid-conveying tubes and has particular reference to the condition of inlet flow of wa'ter into the ends of tubes such as condenser tubes, the chief object being to provide means for reducing the rapid tube wear that occurs in some circumstances as, for example, in the case of the circulating water in the condensers of high speed boats. Such wear is particularly severe at the inlet ends and is known as inlet erosion.

In the case of condenser tubes it is known to project the straight tube ends into packing recesses or stuillng boxes" in the condenser end plates and to embrace the tube ends with packing material and terminating ferrules, the latter having an internal shoulder as an abutment for the tube ends and a suitably flared or streamlined mouth or orifice to promote smooth inflow.

The critical speed at which water owing over the surface of a material overcomes its resistance lto wear is termed the rubbing speed of the material, and it is known that the' so-called rubbing speed of different materials is not the same; for s example, the rubbing speed of the brass of which some brass tubes and ferrules are made is about 8 feet per second, and that of cupro-nickel, which is expensive, is about 12 feet per second. In some cases, however, the speed of the water circulating in condenser tubes becomes as high as 12 to 14 feet pei-second and it 1s therefore evident that in such cases the wear of such tubes and their terminating ferrules is very rapid.

According to the present invention the ferrules associated with the tube ends of. flowing liquid tubes such as ships condenser circulating tubes are made of or lined with a material having a much higher rubbing speed than that of the usual metals or alloys of which they are made. The materials chosen are such as have a rubbing speed approximating or exceeding that of condenser circulating water. For this purpose rubber is very suitable as it has a rubbing speed as high as about feet per second. Other suitable materials are mouldable and thermo-plastic organic compositions. These materials may be used to compose the entire ferrules or may be used asan adherent or removable surface lining or fitting. In some cases the same material may extend for some 'distance along the interior of the tubes themselves. as. for example, in the case of a removable lining in the form of a tube with a suitably ilared or streamlined inlet-end conforming to the shape of the inlet metal ferrule into which it ilts and beyond which it may extend for some distance along the interior of the associ- June 23, 1942, Serial No. 448,134 Great Britain June 16, 1941 ated tube. Alternatively as, for example, inthe case of a metal ferrule with internal shoulder, the rubber or like material may be a coating on the flared mouth and internally as far as the shoulder.

In some cases the same material may extend for some distance along the interior of the tubes themselves, as, for example, lin the case of a removable lining in the form of a tube with a suitably flared or streamlined inlet-end conforming` to the shape of the inlet metal ferrule into which it ilts and beyond which it may extend for v some distance along the interior of the associated tube; in such cases however a friction fit may be insured by making the said lining slightly oval in its natural form throughout its length or at and near the exit end thereof and of such dimensions that by deforming it to the true cylindrical shape, e. g., on a former or by pinching, it can easily be inserted and released, whereupon the oval formation tends to re-assert itself and causes a self-gripping action.

It has -been proposed in connection with condenser tubes having iiared mouths to employ a resilient insert secured by cement or adhesive but by adopting the oval formation referred to the use of cement or adhesive is rendered unnecessary.

In the case of making entire ferrules of rubber or similar composition they may be formed with the usual internal shoulder, and externally they may be threaded to engage threads on the stuffing box Wall or they may be made With a smooth cylindrical exterior of a diameter sufliciently large to form a resilient push fit in the stufng box. The resiliency oi such ferrules will also be of advantage to accommodate longitudinal ex-'L pansions and contractions of the tubes themselves.

If desired the external cylindrical surface of resilient composition ferrules as above described may be' neither smooth nor'screw-threaded but merely roughened or corrugated or ribbed circumferentially withsn extreme outside diameter slightly larger than the diameter of the receiving stufling box or tube plate recess, so that a good grip is secured between the ferrule and the plain or threaded surface of thev said stuiling box or tube plate recess.

Several embodiments of the invention will now be described with reference to the accompanying drawing in which- Y Figure 1 is a longitudinal section of a condenser Figure 2 is a longitudinal section of part of a condensertubeplateanclcontlensertubewitliV packing and with a ferrule composed entirely of rubber.

Figures and 6 are sectional views of a rubber ferrule as in Figure 4, the external surface of Figure 5 being smooth and that of Figure 6 being roughened with rings of screw-thread section.

Figure 7 is a longitudinal section of a modied form of the lining. V

Referring first to Figures 1 and 2 the reference numeral I represents part of a condenser tube sheet carrying a condenser tube 2 the entering end of which abuts against a shoulder or set-back 3 on the entrance ferrule I so that the ferrule surface and the tube surface present no break to set up disturbance in water now.

5 is a ring of nbre packing and 6 is an annular collapsible metal packing forced into position by the ferrule l. I is the lining of rubber or slmilar mouldable or thermoplastic material according to the present invention completely covering the mouth and internal surface of the ferrule 4 and extending for a substantial distance down the condenserl tube 2. In order to ensure `a good nt the lining is of truly circular cross section internally at the entrance and also midway in its length, but slightly oval at and near the exit end. 'Ihis being the natural shape of the lining as manufactured, it will be understood that it has to become deformed into truly cylindrical shape while being inserted and then exerts a pressure on the internal surface of the condenser tube owing to its tendency to'resume its naturally oval shape.

Figure 3 shows a metal ferrule 4 having a lining or facing only as far as its shoulder or setback 3. In this case the depth of the shoulder added to the thickness of the lining is equal to the thickness of the condenser tube so that thereis no sudden break in the surface over which now occurs.

Figures 43 5 and 6 show the use of a com- 2 asumo y condenser tube plate and condenser tube with plete ferrule 4' of rubber or other mouldable or Y packing and ierrule provided with a long lining thermoplastic material formed. as in the case of of the kind shown in Figure 1. the metal i'err'ulel I of Figure 2. with a shoulder Figure 3 is a longitudinal section of an ordior setback l' of sufficient depth to ensure connary metal condenser tube ferrule provided with 5 tinuity oi' its internal surface with the internal an entrance lining according to the invention. metal surface o1' the condenser tube 2. Even if Figure4isalongitudinalsectionofpartofa theexternalsurfaceof theferruleissmooth as shown in Figure 5 it will, if suitably dimensioned, nt firmly by friction in the tube sheet recess, but it may if desired be roughened as for example by being provided with rings ofscrewthread section as shown in Figure 6.

A method of ensuring a good iit yespecially for a lining of the kind shown in Figure 1,' is shown, in Figure 7 where the lining is shown to be ofi truly circular cross section internally at the en-l trance and also midway ln its length, but slightly oval at the exit end. This being the natural shape of the-lining as manufacturedit will be understood that it has to becomedeformed into truly cylindrical shape while being inserted and then exerts a pressure on the internal surface of the condenser tube owing to its tendency to resume its materially oval shape.

What I claim is:

1. For use in combination with straight-end tubes, such as the circulating tubes of condensers, a hollow cylindrical body with an outwardly flared end adapted for insertion and accurate ntting into said tube end, lsaid body being composed of material having a substantially higher rubbing speed than that oi' the metals or alloys normally composing the tube, and having a length of non-circular cross section to insure a tight it in said tube.

2. In condensers and similar liquid-conveying multi-tubular apparatus, the combination of a tube plate recessed and having the inlet endsof a group of tubes supported by said plate and projecting into the recesses thereof, a ferrule in the open end of each recess provided with a lining composed of rubber or mouldable organic plastic and extending inwardly beyond the ferrule as a lining for part of the tube, said lining having a cross sectional shape naturally slightly oval throughout its length or at and near the exit end thereof, substantially as and for the purpose specified.

FRANCIS CLARENCE WALTER WSON. 

